This invention relates to apparatus for adjusting the support provided by a backrest of a chair, and more particularly, to such an apparatus for use with a chair having a backrest with sling back upholstery which may easily adjust the back support provided by the upholstery to meet the particular demands of an occupant of such a chair.
Several types of chairs employ a backrest formed with sling construction for supporting the back of the occupant. Sling construction generally refers to a backrest having foldable, flexible upholstery with two opposing side edges which are anchored by two generally vertical support posts. Sling construction backrests are typically found in chairs which are constructed to be folded, such as foldable wheelchairs, director chairs or the like.
When an occupant of a chair having such a backrest leans against the upholstery of the backrest, the backrest typically supports the back of the occupant at the initial point of contact between the back and upholstery. Typically the initial point of contact is between the upper portion of the back and upholstery. In addition, the support provided by the upholstery of the backrest is distributed fairly evenly in the lateral direction along the back of the occupant.
A drawback of having the back of the occupant supported by such a backrest is that with the upper portion of the back contacting the upholstery of the backrest, the lower portion of the back is not supported. This lack of support may cause discomfort in the lower back.
Sitting in a chair with a sling construction backrest may also promote posterior tilting of the pelvis and rounding of the spine due to the lack of proper pelvic and lumbo-sacral support. This pelvis tilting and rounding of the spine may cause a permanent deformity of the spine and lower back pain.
An additional drawback of the backrest is that because the support is evenly distributed in the lateral direction, such support is not desired if the occupant experiences discomfort when a particular area on the back, such as the spine, is contacted. Also because the upholstery of the backrest typically assumes a particular configuration when leaned against, individual support needs of the occupant, such as an occupant with atrophied back muscles, are not addressed.
An additional drawback of the backrest is the lack of additional support in the upper back region; however, such support should be evenly distributed in the lateral direction.
The above noted drawbacks are compounded when the occupant spends long periods of time in a chair with a sling construction backrest. For example, wheelchair occupants are typically in such chairs for significant periods of time.
In addition, efforts by the occupant to adjust the degree and distribution of support provided by the backrest may be hindered due to the need to be able to fold the chair and backrest. Often, pads or cushions which are placed in the chair must be removed before the chair may be folded which is a drawback.
It is therefore an object of the present invention to provide an improved apparatus for use with a chair having a sling construction backrest for adjusting the support provided by the backrest to correspond to the individual needs of an occupant. A related object is to provide such an improved apparatus to adjust the support provided by the backrest to provide support or additional support at particular locations along the back of the occupant such as the lower and upper regions of the back.
An additional object of the present invention is to provide an improved apparatus for adjusting the back support provided by a chair constructed to be folded.